The present invention relates to a safety device for an elevator door. In particular, it relates to an improvement on the elevator door safety shoe which controls the opening and closing of an elevator door.
An elevator door safety shoe is a plate interposed in the space formed between the elevator car and the floor of each story, and is a safety device that prevents the elevator door from opening and closing when the elevator car makes an abnormal contact, such as colliding, etc. with the plate after the elevator car ascends and stops at each story.
Conventionally, this elevator door safety shoe was controlled with a microswitch which has a cable.
However, in an elevator door safety shoe controlled with a microswitch which had a cable, there were inconveniences concerning low reliability of the elevator door safety device since the cable is bent each time the door is opened and closed, eventually tending to disconnect easily along with the cost of maintenance increasing.
Therefore, the present invention aims to improve on the reliability of the elevator door safety device.
In order to solve the aforementioned problems a safety device for an elevator door characterized by the following facts: a lever with one end pivoted at an elevator door safety shoe has its other end fixed and supported on each floor in a rotatable manner; a polarized reflection plate is supported at one end of a link lever which has its other end pivoted to the aforementioned lever to swing around the pivot point; a detector facing the polarized reflection plate is connected to a controller; and the controller is connected to the door operator. Also, it is characterized by the fact that the detector has an LED as a light emitting element which is opposite an X-axis polarization filter and a photo diode as a light receiving element which is opposite a Y-axis polarization filter.
Therefore, when an abnormality occurs in the elevator door safety shoe, the lever and the link lever rotate in connection with the operation thereof, the polarized light reflection plate tilts, the infrared ray emitted from the detector exactly opposite to it ceases to be reflected at the polarized light reflection plate, an abnormality at the pertinent story is detected, and opening and closing of the elevator door becomes impossible. When the elevator door safety shoe returns to a normal state, the lever and the link rotate in reverse and are restored to the normal state so the polarized light reflection plate is exactly opposite the detector. This type of operation is executed via the lever and the link lever, so failure of the elevator door safety device caused by non-operation of the prior art microswitch due to disconnection of the cable is avoided.